Cylinder arrangement



May 25, 1965 A. w. DUNHAM CYLINDER ARRANGEMENT Filed Feb. 13, 1962 I 2Li- Ansel W. Dunhom IN VE N TOR United States Patent 3,185,943 CYLWDERARRANGEMENT Ansel W. Dunham, R0. Box 242, Tilton, NJi-I. Filed Feb. 13,1962, Ser. No. 172,967 15 Claims. (Cl. 2164) This invention relates toimproved fluid cylinders and to an improved method for assembling thesame. More particularly it relates to pneumatic or hydraulic cylindersof improved construction featuring interchangeable parts, rapidconvertability to a desired function, sturdy structure which is light inweight and which may be rapidly assembled and dismantled.

One of the principal features of this invention is a unique mountingconstruction of the heads of the cylinder to the barrel in such mannerthat the naturally inherent forces induced by internal pressure in theoperation of the cylinder tend to lock the head even more tightly to thebarrel. In this manner there is an increased retaining force between theheads and the barrel at the time of the increased internal pressure ofthe cylinder, whereas this force becomes less as the internal cylinderpressure subsides.

Heretofore the methods of aflixing the heads to the barrel of thecylinder consist of internally threaded heads and externally threadedbarrels, internally grooved heads and externally grooved barrels withsome sort of a retaining ring to prevent separation, or a tie rodconstruction which embodies the use of very heavy heads and tie rodswith all necessary brackets, lock washers, nuts, etc., and whichproduces a highly cumbersome, hard to as semble and to dismantle,unwieldly and generally unattrative cylinder.

The cylinder construction of the present invention provides for afinished product with a high strength-toweight ratio, streamlined inappearance and which may be completely assembled or disassembled in afraction of the time required of conventional cylinders, can beimmediately converted to a double rod cylinder from a single rodcylinder at a minimum outlay of parts and labor to permit maintenance ofa minimum dealer supply and still provide for varying bores and strokesfor immediate availability to the end user. The piston head constructionis a solid one-piece body to which is moulded a one-piece seal as ahomogeneous unit with the body being tapped for holding the rod fromopposite ends, with a dead center to eliminate all possibility ofinternal leakage. The outer or wall contact edges of the piston aremoulded and serrated to provide a multiplicity of Wiping edges, thusrendering the pos sibility of leakage at this point to a minimum. Withthe body unit of the double piston rod head tapped from opposite ends,the live end mounting screw is interchangeable with the dead endmounting screw so that if a two-rod cylinder is required, it may beobtained in a matter of minutes and at negligible cost, whereas withconventional cylinders a completely new cylinder would be needed and thereplaced cylinder discarded. The live or forward end locking screwmember preferably carries a square 0 ring with serrated edges to preventleakage along the piston rod passing therethrough. Since the cylinderinlet and outlet orifices are cast integral with the heads which have nothreaded connection to the cylinder, these orifices may be rotated toany desired degree for connection with the fluid pressure means.

Another principal object of the apparatus and method of the invention isto provide means whereby a fluid pressure cylinder may be assembled inany desired length from ordinary tube having a cylindrical wall ofuniform thickness and having smooth inner and outer faces, by simplycutting the tube to the desired length and assemdiibfi i Patented May25, 1965 bling with the novel cylinder heads of the invention. The priorart step of threading or grooving the cylinder to secure the cylinderheads is eliminated by providing mechanical advantage means on eachcylinder head, for piercing sharp, hard protuberances into the wall ofthe tube during assembly, the bite of the protuberances into thepreferably softer material of the tube firmly anchoring each headagainst axial movement under cylinder pressure. The force exerted on thehard protuberances is preferably outward against the inner face of thetube, or cylinder, and is opposed by an encircling flange on thecylinder head, forming a rigid, unyieldable socket of pre determineddepth for receiving the end of the tube, or barrel, thereby assuringthat even thin walled tubes will not be deformed or fractured during theassembly operation.

For a more complete understanding of the present invention, reference isnow made to the drawings wherein:

FIGURE 1 shows a cross-sectional view of the cylinder,

FIGURE 2 shows an extension used to foreshorten the piston strokewithout foreshortening the cylinder,

FIGURE 2A is an enlarged somewhat diagrammatic, fragmentary view showingthe sharp hard protuberances on the expansible ring piercing the softerinner face of the side wall of the cylinder to secure a plurality ofanchor ing bites,

FIGURE 3 is a cross section of an alternative head preferably used inhydraulic applications,

FIGURE 4 is a side view of the expandable locking ring,

FIGURE 5 is an elevational view of the locking ring expanding member,and

FIGURE 6 is a plan view of the locking ring expanding member.

Referring now to FIGURE 1, there is shown a cylinder 10 having cylinderheads 11 and 12 attached at each end through expanding locking rings 13,14; looking ring expanding members 16, 17; and a livehead lock-up screw18 adapted to receive the piston rod therethrough and a deadhead lockupscrew 19 at the other end as will be more fully explained hereinafter.The heads become secured to the cylinder more tightly as pressure isapplied internally to actuate the piston rod. The dead end lockup screw19 is threadably engageable with locking ring expanding member 17. Asplit ring 22 spaces the head of the lockup screw 1 from the cylinderhead 12 in the absence of a mounting member as shown. A similar splitring 23 spaces the head of the lockup screw 18 from cylinder head 11.The walls of both split rings are of a truncated, conical configurationso as to provide a smooth finished appearance as shown by split ring 22and, by reversing the taper of the truncated conical outer surface, itlocks a mounting member 24 in place as shown. The mounting member maythen be fastened to a suitable structure for retaining the cylinder in afixed position. A mounting member may be secured on the other end bysimply backing up the lockup screw 19 to allow reversing of the splitring 22 over the mounting member, and re-tightening the lockup screw tosecure the mounting member. Suitable input and output orifices 26 and 27in cylinder heads 11 and 12 communicate with the interior of thecylinder through suitable passageways 28, 29 of locking ring expandingmembers 16 and 17 The livehead lockup screw 18 has a bushing 31 and aseal 32 through which the piston rod 33 passes. The outer end of the rod33 is locked into a rod clevice 34 with a locked nut 36. Pin 37 connectsthe piston rod 33 to apparatus to be actuated thereby. Seal 32 ispreferably square 0 ring with serrated edges to provide for a pluralityof wiping surfaces.

The piston head 38 is a solid one-piece body to which is moulded thewiping seal 39 as a homogeneous unit. The piston head 38 is tapped toreceive a piston rod at either end, but these tapped openings do notcommunicate with each other and thereforeall possibility of leakagethrough the piston head is entirely eliminated. The serrated contactingsurfaces of seal 3? provides a multiple of wiping surfaces against theinner surface of cylinder to thereby provide for a very etficient sealwith a minimum of leakage and pressure. It should be noticed that theseal extends laterally beyond its connection with the piston head sothat internal pressure forces the seal into greater wiping contactrelationship with the cylinder wall.

The serrations 4t) slant inwardly from the ends and it is the trailinghalf of the serrations that provide the multiple wiping action. Forexample, when internal pressure from the left forces the piston head tothe right, the pressure urges the left half of the serrations in wipingcon-tact. This type of seal is particularly effective on scored orpitted cylinder barrels. The locking ring expanding members 16, 17 havea circular extension 41 which cooperates with the cushioning wall 42 ofpiston head 38 to provide a cushioning when the piston has reached itsend of the stroke. Fluid trapped therebetween may escape throughsuitable openings 43 topermit the piston to complete its stroke. Theseopenings may be made adjustable in size to provide controlled escapementas desired or they may be preselected in size.

In FIGURE 2 there is shown an extension 44 which is threadablyinsertable into opening 46 ofdead head lock-up screw 19. The threadedshaft 47 may be of any desired length and the cylindrical extension 48also may be of a desired length to stop the piston head 38 when itpasses within the cushioning wall 42 thereon.

As shown in the cross-sectional view in FIGURE 3 of an alternate headconstruction, the cylinder ltlis gripped on the inner wall with thelocking ring 13 in a manner similar to that shown in FIGURE 1. Thecylinder head 12a, however, has an inner tapered recess 49 in which ispositioned another locking ring 59' to additionally grip the outersurface of cylinder 10. This recess 49 is longer than the locking ring59 contained therein to permit lateral movement thereof. This lateralmovement of the ring against the tapered recess causes further inwardmovement of the ring against the cylinder. Thus, as the internalcylinder pressure increases, the gripping pressure to retain thecylinder head on the cylinder also increases. For this reason, thisembodiment is preferably used in hydraulic pressurization involvinghigher pressures.

Referring back to FIGURE 1, it should be noted that as the lock upscrews 18 and 19 are tightened, the locking ring expanding members 16and 17 move outwardly, and with their tapered outer surface they Urgethe locking rings into tighter gripping relationship with the cylinder10. As the internal pressure increases, there is a tendency for thecylinder heads 11 and 12 to move longitudinally away from the cylinderbarrel 10. This in turn causes the locking ring expanding members 16 and17 to be urged outwardly thereby increasing the locking ring contactwith the inner wall of the cylinder 10 to thereby provide a greatergripping effect, thus withstanding the greater forces to which thecylinder heads have become subjected.

FIGURE 4 is a side view of the locking ring. This thin side-walledtubular steel ring has an inner surface 51 tapered approximatelyseven-degrees to present a truncated, conical space to receive thelocking ring expanding members 16 or 17 that are adapted to fit therein.The outer surface 52 is cylindrical in form and has buttressed threadsfor engaging the inner wall of the cylinder. A buttressed thread isdefined as one that has an outwardly extending side and a tapered side.The tapered side 53 slopes outwardly toward the same end 54- of the ringas the smallest diameter 56 of the inner surface 51. Other knurled orfriction surfaces also may be used. The walls 53 of the ring are slottedalternately from opposite ends of the ring to predetermined depths toachieve flexibility. One slot 59 extends from end to end to permit theexpansion and contraction of the ring.

FIGURE 5 and FIGURE 6 is a plan and elevational view of the locking ringexpanding member 16. This consists of an internally threaded nut 61 witha truncated, conical exterior surface 62 cooperatively engageable in amating pitch with the inner surface 51 of the locking ring 13 (seeFIGURE 4) whereby lateral movement of the nut will cause outwardexpansion of the ring to grip the inner surface ofthe cylinder wall. Ithas an outwardly directed end 63 extending toward the end of thecylinder and an inwardly directed end 64 extending to ward the center ofthe cylinder.- The inwardly directed end has a cylindrical extension ormale ring 41 machined thereon which mates with the cushioning wall 42 inthe piston head 38 (see FIGURE 1) to achieve a cushioning effect. Thefluid entrapment therebet-ween is controlled through the opening 43 inthe piston head 38. Extending inwardly from the outwardly directed end63 of the expanding member 16 is an annular bottomed groove 66 betweenthe threaded inner surface 67 of nut 61 and the conical surface 62.Axially extending slots 68 extend from the outer surface 62 inwardly tothe inner edge of the groove 66. The groove 66 and slots 68 provideflexibility in the external surface 62 to provide a continuous pressureaction on the locking ring 13 that would not otherwise be obtainablewith a non-resilient type member.

As best shown in FIGURE 2A, the cylinder barrel 10 may be cut to thedesired. length from ordinary tube having a cylindrical wall 76 ofuniform thickness, a smooth, ungrooved, unthreaded, outer face 71 and asmooth, ungrooved, unthreaded, inner face 72. Each cylinder head, suchas 12 is provided with a flange 73 encircling the adjacent end of thebarrel 10 for resisting and oposing outward pressure especially when theWall 7% is relatively thin. The inner face 74 of each flange 73 issmooth for slidably engaging and fitting the outer face 71 of the end ofthe barrel 10 seated within the head 12 and includes an annular groove75 for a seal such the the O-ring 76.

The outwardly expansible anchoring ring 13, when in its normallycontracted condition, slides within the end of barrel 10, but isprovided with the plurality of sharp, hard protuber-ances indicated at78 and formed by the buttressed threads 79 or by equivalent metalpiercing elements. Upon exertion of outward radial pressure by themechanical advantage means 80, which preferably consists of theexpanding member 17 operable by the threaded lock-up screw 19 from theoutside of the head, the sharp, hard edges, or points, 78 pierce intothe inner face 72 to firmly anchor the head against axial movementrelative to the barrel. Each head such as 12 includes a smooth axialbore 20, having a suitable fluid seal 21 therein, in which the lock-upscrew such as 19 is turnable and slidable.

The lock-up screw, or bolt, 19 is tapped at 82 for convenience inmounting the cylinder or mounting other parts on the cylinder.

It will be understood that the material of the sharp, hard protuberances78 is of a hardness sufiicent to bite or gouge, a minute distance belowthe plane of the inner face 72 of the barrel 10 although it is notnecessary that each protuberance pierce an equal distance or that allprotuberances secure an identical grip. While merely roughened metal tometal surfaces, with substantial outward force, normal to the axis ofthe barrel 10, and exerted by mechanical advantage means 80, mightcreate suflicient boundary friction to make a satisfactory low pressurecylinder, such frictional gripping means, is not contemplated herein. Inthe method and apparatus of this invention, the cylinder heads are each.firmly anchored against axial movement by an actual penetration into thematerial of the barrel to the extent that they cannot be moved while theexpansible ring is in expanded condition despite internal pressures of150 p.s.i.

or more.

It has been found that a barrel it cut from a tube of relatively softmetal such as tool steel or manganese steel and an expansible ring 13,with sharp teeth or protuberances 78 of relative.y hard metal such ashigh carbon steel, when assembled into a cylinder in accordance with theinvention with the outward pressure exerted by the mechanical advantagemeans 80 will have an indentation, or impression, 83 with a depth whichis perceptible to the human eye in the form of a shallow, sometimesinterrupted annular groove for each annular protuberance. A cylinder, somade, has been operated under a fluid pressure of 150 p.s.i.continuously for several months with no leakage and with no axialmovement of the heads.

It will also be understood that while the inner face of the barrel mayshow no marks at all when the device is disassembled after use, theexpanding protuberances may have created a deformation therein whichresumed its original shape upon release of pressure. It is believed thatthe outward pressure of the expanding locking rings increases duringincrease of pressure within the barrel by an outward movement of theexpanding members which is imperceptible and therefore not shown.

It i my theory that the seven degree inclined mating surfaces, whenpolished, lubricated or sleeved with Teflon will convert a one poundaxial pull on the expanding member 16 into at least a 4.32 pound outwardforce against the inner face of the barrel 10. Where the steel barrel isabout three inches in inside diameter and .062 inch in thickness, thecircumferential stress on the barrel may then be calculated by theformula Internal pressureX inside diameter If 60,000 p.s.i. is taken asa safe circumferential stress for a cylinder tube then =8-i0 lb.=safepull on expanding member A safe torque on the lock-up screw 19, toachieve up to an 840 lb. pull on the expanding member, has beencalculated to be up to about 78.5 inch pounds.

Whether the sharp edges, or points, '78 make a temporary deformation ora permanent deformation in the inner face of the barrel, it will beapparent that the cylinder heads 11 and 12 are firmly anchored againstaxial displacement when sufficient torque is applied to the lockingscrews, with little danger of rupture of the barrel, especially in viewof the encircling flange '73 on each head.

While my invention concerning the utilization of selfinduced lockingforces to oppose the pressures of separation has been explained inconnection with the retention of heads on an actuation cylinder, thissame principle may be applied in other areas such as in joining orcoupling of pipes or tubing, or closures to pressure vessels of anysize.

The step of the method of my invention wherein the cylinder barrels maybe cut from commercially available seamless tubing of any desireddiameter and wall thickness permits a local dealer to fill orders forfluid cylinders without delay. Because the resulting cylinder barrelsneed not be threaded, or grooved, to retain my improved cylinder heads,costly machinery need not be used to affix the heads and the wallthickness of the tubing may be at a minimum.

Having thus described the invention and the embodiments thereof, it isdesired to emphasize that many modifications may be resorted to in amanner limited only by a just interpretation of the following claims.

What is claimed is:

1. An improved high strength-to-weight cylinder comprising:

a cylinder barrel having smooth inner and outer walls,

cylinder heads at each end of said barrel, each having a smooth axialbore and having an integral annular flange of predetermined lengthforming a socket slidably receiving an end of said barrel and adapted toresist outward pressure,

pressure openings in said heads to pass pressure fluid into saidcylinder barrel,

said cylinder heads normally being urged outwardly by internal pressurewithin said barrel,

means at each opposite end of said barrel for retaining said heads onsaid barrel ends, each said means comprising:

an outwardly expansible locking ring of hard metal, within the socket ofeach said head, said ring having sharp protuberances engaging the innercylinder barrel wall opposite the flange of said head,

a locking ring expanding member for urging outward expansion of saidlocking ring against said inner wall, and

a lockup screw in said axial bore, and operable from outside said headfor drawing together said cylinder head and said expanding member tothereby cause said locking ring to expand against said barrel withinsaid socket.

2. The improved cylinder as defined in claim 1 wherein said locking ringexpanding member has a truncated conical configuration with a taperedouter surface having a plurality of radially extending slots therein forresilient flexibility thereof, and

said locking ring has a truncated conical inner surface having aplurality of slots extending alternately from each opposite end thereoffor receiving said expand ing member therein, and

wherein the tapered outer surface of said locking ring expanding membermates with said locking ring inner surface.

3. The improved cylinder as defined in claim 1 wherein said locking ringexpanding member includes a plurality of radially extending dead endslots, each extending alternately from an opposite end thereof forresilient flexibility, and whose inner configuration is an internallythreaded nut for receiving said lockup screw.

4. The improved cylinder as defined in claim 2, Wherein said lockingring expanding member has orifices therethrough to permit fluid flowfrom the pressure openings in said cylinder heads to the interior ofsaid cylinder barrel.

5. The improved cylinder as defined in claim 1 wherein said ring isformed of one piece of hard steel with a truncated, conical, innersurface having a longitudinal slot extending across said ring to permitexpansion, and

partial slots extending inwardly from alternate ends of said ring forflexibility to thereby permit the outward expansion of said ring toengage said inner cylinder wall.

6. The improved cylinder as called for in claim 1 wherein a truncatedconical split ring is used to properly space the head of one of saidlockup screws from its associated cylinder head, and wherein saidtruncated conical ring may be inverted to thereby retain a mountingmemher.

7. An improved high strength-to-weight piston cylinder comprising acylinder barrel having a cylindrical wall of uniform thickness withsmooth inner and outer faces;

a pair of cylinder heads, each having a flange encircling one of theopposite ends of said barrel and forming 7 a socket of predetermineddepth. for resisting outward pressure, a smooth inner face on saidflange engaging the smooth, outer face of said wall and a fluid passagecommunicating with the interior of said barrel, and means for retainingsaid heads on the ends of said barrel, said means comprising anoutwardly expansible anchoring one piece, metal,

ring within each said head, said ring having a plurality of sharp, hardprotuberances on the outer face thereof in engagement with, and adaptedto pierce into, the inner face of the portion of said wall within saidsocket and mechanical advantage means mounted on each said head andoperable from the outside thereof, said means being operably connectedto said anchoring ring to outwardly expand the same for piercing saidprotuberances into said wall thereby firmly anchoring said heads againstaxial movement relative to said barrel. 8. The improved cylinder asdefined in claim 7 wherein said anchoring ring includes a tapered,slotted inner face and said mechanical advantage means comprises anaxially movable expanding member having a tapered, sloted outer face inengagement with the inner face of said ring and having fluid passagewayscentrally thereof and threaded mechanism for drawing together saidcylinder head and said expanding member to thereby expand said ringoutwardly. 9. The improved cylinder as defined in claim 7 wherein saidbarrel is of metal and said protuberances are a plurality of axiallyspaced buttressed threads, each terminating in a sharp annular edge ofhard steel at least equal in hardness to the metal of said barrel.

10. An improved fluid pressure cylinder and head structure comprising:

a cylinder barrel having a cylindrical wall of uniform thickness withsmooth outer and inner faces;

a cylinder head having an integral, annular flange slidably fittingaround and encircling the outer face of one end of said barrel, saidflange extending longi tudinally therealong a predetermined distance toresist outward pressure of expansible retaining means within said end ofsaid barrel, and

said expansible retaining means within said end of said barrel, saidmeans including an outwardly expansible locking ring formed of one pieceof hard metal having a series of sharp hard protuberances extendinglongitudinally and circumferentially therearound in engagement with thesmooth inner face of the portion of said barrel encircled by saidflange,

and mechanical advantage means on said head, operable from the outsidethereof, said means being operably connected to said ring to outwardlyexpand the same for piercing said protuberances into said wall andanchoring said head to said barrel.

11. The structure defined in claim 10 wherein said head includes a fluidpassage communicating with the interior of said one end of said barreland said mechanical advantage means includes a fluid passage connectingsaid one end of said barrel to the remainder of the interior of saidbarrel.

12. The improved cylinder as defined in claim 1 wherein the lock-upscrew in the cylinder head at one end of said barrel is dead head with athreaded deadend opening in the inner face thereof and the lock-up screwin the cylinder head at the other end of said barrel includes a smoothaxial bore for slidably receiving a piston rod.

13. The improved cylinder as defined in claim 1 wherein said lockingring expanding member includes a truncated conical exterior surfacehaving axially extending slots for providing resiliency and an inwardlydirected end having an unslotted central portion with a cylindricalextension thereon for mating with a corresponding portion of a pistonhead.

14. The improved cylinder as defined in claim 12 plus a detachablemember having a cylindrical extension thereon for mating with acorresponding portion of a piston head on said piston rod and having athreaded shaft insertable in said deadend opening in said lock-up screw.

15. The improved cylinder as defined in claim 10 plus: an inner taperedsurface in the flange of each said cylinder head forming an innertapered recess therein, and

an inwardly contractable locking ring, positioned within said recess,said ring having sharp, hard protuberances in engagement with the smoothouter face of the portion of said barrel encircled by said flange, andhaving an outer tapered surface mating with the inner tapered surface ofsaid flange;

whereby normal tendency toward lateral movement of said head due toincreased inner cylinder pressure causes said locking ring to contractinwardly more tightly around the end of said barrel.

References Cited by the Examiner UNITED STATES PATENTS 778,068 12/04Peterson 220-245 1,068,793 7/13 Mason 220-24.5 1,459,542 6/23McCatheron.

2,218,581 10/40 Levan. 2,363,142 11/44 Reed. 2,432,996 12/47 Larson etal. 2,870,794 1/59 Thaxton 220-245 X FOREIGN PATENTS 17,541 12/87 GreatBritain. 101,390 9/ 16 Great Britain.

FRED E. ENGELTHALER, Primary Examiner.

KARL I. ALBRECHT, SAMUEL LEVINE, Examiners.

1. AN IMPROVED HIGH STRENGTH-TO-WEIGHT CYLINDER COMPRISING: A CYLINDERBARREL HAVING SMOOTH INNER AND OUTER WALLS, CYLINDER HEADS AT EACH ENDOF SAID BARREL, EACH HAVING SMOOTH AXIAL BORE AND HAVING AN INTEGRALANNULAR FLANGE OF PREDETERMINED LENGTH FORMING A SOCKET SLIDABLYRECEIVING AN END OF SAID BARREL AND ADAPTED TO RESIST OUTWARD PRESSURE,PRESSURE OPENINGS IN SAID HEADS TO PASS PRESSURE FLUID INTO SAIDCYLINDER BARREL, SAID CYLINDER HEADS NORMALLY BEING URGED OUTWARDLY BYINTERNAL PRESSURE WITHIN SAID BARREL, MEANS AT EACH OPPOSITE END OF SAIDBARREL FOR RETAINING SAID HEADS ON SAID BARREL ENDS, EACH SAID MEANSCOMPRISING: AN OUTWARDLY EXPANSIBLE LOCKING RING OF HARD METAL, WITHINTHE SOCKET OF EACH SAID HEAD, SAID RING HAVING SHARP PROTUBERANCESENGAGING THE INNER CYLINDER BARREL WALL OPPOSITE THE FLANGE OF SAIDHEAD, A LOCKING RING EXPANDING MEMBER FOR URGING OUTWARD EXPANSION OFSAID LOCKING RING AGAINST SAID INNER WALL, AND A LOCKUP SCREW IN SAIDAXIAL BORE, AND OPERABLE FROM OUTSIDE SAID HEAD FOR DRAWING TOGETHERSAID CYLINDER HEAD AND SAID EXPANDING MEMBER TO THEREBY CAUSE SAIDLOCKING RING TO EXPAND AGAINST SAID BARREL WITHIN SAID SOCKET.